Spike pins for use on vehicle tires, shoe soles or tip ends of walking sticks to provide non-skidding function on ice and snow-covered roads have heretofore been made of metal.
However, it has been found that metal spike pins, especially ones used on vehicle tires may shave the road surface when they are covered with no ice or snow and produce dusts, posing an environmental problem, so that the use of metal spike pins has come to be regulated. In view of this, researches have been extensively conducted in search for new materials to replace metal for making spike pins.
In this regard, improvements on so-called studless tires have been made to modify the properties of the rubber itself of which tires are formed such that the rubber may be maintained in a soft condition even at a low temperature and may have an enhanced adhesiveness of the rubber to the ice and snow.
On the other hand, an attempt has also been made to make spike pins of other materials than metal such as synthetic resin or hard rubber for example.
As new materials, spike pins made of hard rubber have been proposed; for example, rubber compounds having a property of being in a softened state at a normal temperature and hardening at a low temperature (as disclosed in Japanese Patent Application Sho 63-235771 assigned to the assignee hereof) and rubber compounds having an increased hardness (as disclosed in Japanese Patent Application Hei 2-274240 assigned to the assignee hereof) have been developed.
In addition, spike pins made of metal for use on vehicle tires, shoe soles, or shoes of walking sticks as non-slipping means against ice and snow-covered roads have conventionally been mounted in such a manner that the spike pins protrude from the tread surface comprising the spike-mounting surface.